Libya conflict: Interim forces advance on Sirte

Forces loyal to Libya's transitional government have launched a major assault on the city of Sirte, one of the last Gaddafi strongholds.

Hundreds of vehicles have advanced on the city from both the east and the west and are close to the centre.

Thousands of civilians have already left Sirte but many more are thought to have remained behind.

The BBC's Jonathan Head, on the city's outskirts, says it is by far the biggest assault in recent days.